Since we're in the wilds of 2019 and keys are not as eternal as we once thought they were, I need to say this:
This key is an old key. It was purchased several years ago. To the best of my knowledge, it's as fresh as it was the day it was bundle-bought. I haven't used it, and I haven't given it away. However, many indie developers revoke unused keys these days for no reason, so it's not possible to rely on keys the way we did once.
If the key doesn't work, please contact me. If I can fix the issue I certainly will.